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April 21, 2013

ACE Inhibitors Could Reduce Radiotherapy Damage To Heart and Lungs

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redOrbit Staff & Wire Reports - Your Universe Online

Damage to the heart and lungs caused by treating tumors in a person´s chest area can be limited through the use of drug typically used to treat cardiovascular disease, a team of Dutch researchers claim in a new study.

Dr. Sonja Van der Veen of the University Medical Centre, Groningen (UMCG), and colleagues intended to find out whether or not angiotensin-converting enzyme (ACE) inhibitors could help prevent a condition known as radiation-induced lung toxicity (RILT). Their findings were presented Sunday at the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO).

Lung tissues, including blood vessels, are often damaged when radiotherapy is used to treat breast cancer, esophageal cancer, Hodgkin's lymphoma, and similar conditions — and previous research had linked damage to blood vessels with the development of RILT, the researchers explained. So they exposed the lungs or heart (or both) in rats to radiation and then administered the ACE inhibitor captopril immediately after treatment. The lung functions of the rodents were then measured every two weeks.

“After eight weeks, when early lung toxicity is usually at its height, we found that captopril improved the rats' heart and lung functions, but we were surprised to find that this only occurred when the heart was included in the irradiation field,” Dr. Van der Veen said in a statement.

“This was not due to protection of the lung blood vessels, which were equally damaged with or without captopril,” she added. “So we investigated further and found that the captopril treatment improved the heart's function and decreased the level of fibrosis in the heart soon after irradiation. So these new findings show that ACE inhibition decreases RILT by reducing direct acute heart damage.”

Typically, irradiating the heart results in fibrosis, which causes it to become stiff, resulting in problems with the relaxation of the left ventricle. This, in turn, hinders blood flow from the lungs into the heart, leading to potential pulmonary damage. However, Dr. Van der Veen´s team discovered treatment with captopril resulted in an improvement in the ventricular relaxation of the rats´ irradiated hearts.

The Dutch research team is now teaming with colleagues from the Mayo Clinic in Rochester, Minnesota to design a randomized clinical trial building on their research. The clinical trial will feature patients who had been treated with radiotherapy in the thoracic area (including the heart), and each study participant will be provided with an ACE inhibitor or a placebo following the radiation treatment.

“We are confident that our clinical trial will see the same protective effect in humans as that which we have seen in rats,” said Dr. Van der Veen. “We will also now begin to study the late effects of ACE inhibition on RILT to see whether it affords similar protection. We believe that our results suggest a promising strategy for shielding patients from radiation damage and improving their quality of life, while at the same time allowing them to receive a high enough dose to ensure the effective treatment of their cancer.”